M1 fibre broadband services are down, said the telco in Facebook post just after noon on Wednesday.
"Dear customers, you may experience difficulties in accessing your fibre broadband services," wrote M1. "We are currently rectifying the issue and apologise for the inconvenience."
M1 has in recent years grown its share of fibre broadband customers in. It had 90,000 such customers in the first quarter of this year, up from 30,000 a year ago, said the telco last month.
This latest service interruption comes a week after M1 rivals Singtel was fined $6 million - the largest penalty ever for a telco - over a blaze at its Bukit Panjang Internet exchange last year that took down phone lines, banking, payment and Internet services across Singapore.
The Infocomm Development Authority (IDA) said last week that the disruption affected close to 270,000 subscribers, including home fibre broadband users of SingTel, StarHub and M1, among others. The hour-long fire on Oct 9 last year was caused by the use of an unauthorised blowtorch by a SingTel staff member during maintenance works.